The Langridge glass grinding slab is an 8mm thick glass slab used for the manufacture of artists paint. It has an etched face for the high-shear grinding of pigment with binders.
Take a handful of pigment, make a well in it and pour in about a tablespoon of oil.
Mix into a stiff paste using a palette knife.
Grinding is best done standing, applying pressure whilst moving a muller in a figure of eight motion on the glass slab.
Periodically scrape paste into the centre of the slab and off the muller.
When properly ground no grains should be seen and no grittiness may be heard or felt.
Store the paint in containers such as empty paint tubes or clean glass jars with airtight lid.
Pigment to oil ratios vary depending on chosen pigment. Always try to make paint with the minimum of oil to produce a workable consistancy, thereby minimising yellowing and wrinkling.